As one type of contact lens, there has been known multiple use contact lenses that are used repeatedly over several days. For example, this includes soft contact lenses which are not disposable (so-called throwaway), and soft contact lenses which are not thrown away in one day even among the disposable types, and the like. This kind of multiple use contact lenses are stored and kept in a storage container in a state immersed in storage solution when removed from the eyes at bed time, and the like.
Storage containers for holding this kind of multiple use contact lenses are typically constituted including a roughly dish shaped storage portion for storing the contact lenses in an immersed state in which storage solution is accumulated, and a lid member for covering the opening portion of the storage portion (e.g. see Patent Document 1 (JP-A-2000-281162)).
Then, this storage container, over a suitable period, for example every day, is used multiple times with repeated contact lens storage and removal. Because of that, with the storage container, there is a demand by users to be able to easily take out the contact lenses stored within the container.
To deal with that kind of demand, with storage containers of the conventional constitution, the inner surface of the container has a suitably rough surface to prevent sticking of the contact lenses to the inner surface. Also, for the same purpose, there were also items for which a polyhedron shape connected by a curved line extending in the longitudinal direction of the container inner surface was used.
Furthermore, there were many items for which a suitable guide irregularity was added to the inner surface of the container bottom to make it possible to easily pull up the contact lens toward the opening portion from the bottom portion of the storage portion while pressing the contact lens with a fingertip inserted from the opening portion of the storage portion. This guide irregularity is formed, for example, by a plurality of projections respectively extending radially toward the opening portion from the center of the bottom of the storage portion.
Meanwhile, in recent years, there are reports of an increase in eye diseases in contact lens users, and whether those are true or false and what the cause is are being studied.
Here, the inventors of the present invention, as a result of arduous research regarding the causes of disease in contact lens users, focused on the possibility that an improper storage state of multiple use contact lenses like those described above is one cause of these. Specifically, when the inventors of the present invention did testing regarding storage containers with the conventional constitution, we found the generation of biofilms on the inner surface of the storage portion. A biofilm means an aggregation of bacteria agglomerated together in a film state, and when a biofilm forms, the bacteria inside the biofilm are protected from antibacterial agents, so sterilization is difficult. Because of that, when a biofilm is formed in the inner surface of the storage portion, even when the inside of the storage portion is filled with an antibacterial storage solution, the bacteria protected by the biofilm adhere to the lenses, and thus it became clear that there is a risk of causing bacterial infection by this entering the eyeball.
Furthermore, this kind of contact lens storage container is typically sold as a set with storage solution, and when newly purchased when the storage solution runs out, it is assumed that the storage container will also be replaced and the new one used. However, there are many users who do not follow the assumed use method, and this is a cause of biofilms occurring relatively early, and is conjectured to be one factor in the increase in eye diseases in contact lens users in recent years.
In light of this, a number of storage containers have been proposed which have special processes or the like implemented to suppress the formation of biofilms, but all of them are difficult to put into practical use.
In specific terms, for example a contact lens storage container for which a polymer material containing an antimicrobial agent is formed is disclosed in Patent Document 2 (JP-A-2005-511427). However, the polymerization of an antimicrobial agent itself brings on higher costs, and also, there is the problem that further costs are incurred to sufficiently guarantee safety of the antimicrobial agent, so this is poor in terms of practical usability.
Also, in Patent Document 3 (JP-A-2002-526184) and in Patent Document 4 (JP-A-2002-6274) proposed is giving a photocatalytic function to the contact lens storage container. However, these methods also bring on high costs. In fact, the photocatalytic function is an item that exhibits an antibacterial effect under light, so it is in a form for which the storage portion inner surface is covered by a lid portion or the like, and with contact lens storage containers many of which are kept in a dark location such as indoors or inside a bag or the like, not enough light reaches the storage portion inner surface, and because of that it is difficult to exhibit a sufficient antibacterial effect.    Patent Document 1: JP-A-2000-281162    Patent Document 2: JP-A-2005-511427    Patent Document 3: JP-A-2002-526184    Patent Document 4: JP-A-2002-6274